1. Field of the Invention
The instant invention relates to highly concentrated, low volatile organic compound (low VOC) aqueous agrochemical compositions and methods for preparing same.
2. Technology Description
When agrochemical actives are relatively water soluble, preparing, storing, and shipping same in a commercially acceptable form can be a relatively simple matter. However, many, if not most, agrochemical actives are not very water soluble and formulators are constantly using their ingenuity to find means for preparing these materials in stable formulations that deliver maximum loading of active ingredient per unit volume to the end-user. One means of doing this is to prepare dry formulations such as wettable dispersible granules (WDG's) or wettable powders (WP's) encapsulated, for example, in water soluble bags or containers. Although such dry formulations are attractive not only from a loading delivery viewpoint, but also from a handling and/or worker safety viewpoint, not all water insoluble agrochemicals are able to be dry formulated.
The most straight-forward approach to preparing concentrated liquid formulations with agrochemical actives, e.g., pesticides having limited aqueous solubility, has been through the use of aromatic organic solvent systems. In such systems, aromatic organic solvents such as xylene or kerosene are used to solubilize the pesticidal compound of interest.
Commonly, surfactants are added to the pesticide-solvent compositions to form emulsions. The surfactant-emulsifiers interact with the pesticides in a number of ways both before and during actual use, i.e., application to the site. The surfactants, usually a pair of nonionic and anionic surfactants, can initially disperse and/or emulsify the pesticide in the solvent or in an inert carrier media and, for example, with herbicides, the surfactant composition may also act as a penetrant, spreader, sticker, stabilizer, wetting agent, and defoamer. The surfactant composition may affect the rate of drying of a droplet on a plant and the nature of a residue liquid, or crystal. The surfactants may also influence the weathering characteristics of a pesticide, including its rewetting characteristics.
The presence of the volatile organic compounds in these formulations, together with the surfactants, enable stable emulsifiable pesticidal concentrates (EC's) to be prepared. Although such EC formulations have played and continue to play a major role in the pesticidal market, they have a significant drawback in that the formulations are commonly based on the use of considerable quantities of the highly volatile organic compounds (high VOC's). These high VOC's create both toxicological and ecotoxicological problems. As a result, many government agencies such as the United States Environmental Protection Agency and the European Economic Community Council are proposing legislation and many countries such as Germany and Canada are now requiring eco-labeling of formulations which contain high VOC's.
Thus, to reduce not only the deleterious effects upon the environment, but also the potential for hazardous worker exposure situations, especially in closed environments such as greenhouses, agricultural/chemical manufacturers and formulators continually seek ways to deliver highly loaded, stable agrochemical active formulations to the end-user with significantly reduced levels of high VOC's and preferably without their presence.
To avoid the use of high VOC's in certain pesticidal formulations, Lubetzky, et al. in EP publication numbers 669,078 and 670,113 have disclosed the use of rosin and rosin derivatives that are insoluble in water to "plasticize" certain pesticides and thus to prepare pesticidal emulsions in water (EW's) and emulsifiable concentrates (EC's). By the term "rosin derivatives insoluble in water" Lubetzky, et al. include "hydrogenated rosin, polymerized rosin, methyl esters of rosin or of hydrogenated rosin, glycerol esters of rosin or hydrogenated rosin, triethylene glycol esters of rosin or hydrogenated rosin and pentaerythratol esters of rosin or hydrogenated rosin". By utilizing the above-identified rosin and rosin derivatives as plasticizers, Lubetzky, et al. are apparently able to slightly increase the pesticidal loadings in the EW's and EC's above that realizable in standard high VOC formulations.
It would be very desirable to be able to provide agrochemical formulators with the means to prepare aqueous pesticidal emulsions from stable water-soluble pesticidal emulsion concentrates having very high pesticide loading levels in the absence of environmentally unfriendly, highly volatile organic compounds.